Asus K8N-E Deluxe power down problem

I put together my new system last weekend and have a strange problem when I turn it on. The machine will power off within 1-2 seconds. If I try again it will work 2nd or third time. There are no problems with restarts. Once it's up and running it is totally stable so far. I have applied up to a 10% OC in windows but nothing in the BIOS.